Seversk Technological Institute

The problem of water contamination by long-living cesium and strontium radionuclides is an urgent environmental issue. The development of facile and efficient technologies based on nanostructured adsorbents is a perspective for selective radionuclides removal. In this regard, current work aimed to obtain the nanostructured magnetic zeolite composites with high adsorption performance to cesium and strontium ions. The optimal conditions of hydrothermal synthesis were established based on XRD, SEM-EDX, N2 adsorption-desorption, VSM, and batch adsorption experiment data. The role of chemical composition, textural characteristics, and surface morphology was demonstrated. The monolayer ion-exchange mechanism was proposed based on adsorption isotherm modeling. The highest Langmuir adsorption capacity of 229.6 and 105.1 mg/g towards cesium and strontium ions was reached for composite obtained at 90 °C hydrothermal treatment. It was shown that magnetic characteristics of zeolite composites allowing to separate spent adsorbents by a magnet from aqueous solutions.

We present results of an experimental and theoretical study of the magnetic properties of soft magnetic gels consisting of micron-sized magnetizable particles embedded in a polymer matrix. Experiments demonstrate hysteretic dependences of composite magnetization on an applied magnetic field and non-monotonic, with maximum, dependence of the sample susceptibilities on the field. We propose a theoretical approach which describes the main physical features of these experimental results.

Abstract Chemical–physical properties of ultra‐high‐molecular weight polyethylene (UHMWPE) treated by direct fluorination, direct fluorination accompanied with UV irradiation, by XeF 2 and by TbF 4 , were tested by FTIR spectroscopy, visible spectroscopy, 19F and 13C NMR, scanning electron microscopy, XRD, and EPR. Surface energy measurements were carried out. The direct fluorination of UHMWPE is a diffusion‐controlled process, but treatment with XeF 2 is a kinetically controlled one. Direct fluorination and direct fluorination accompanied with UV irradiation results mainly in a formation of CF 2  groups. On the contrary, CHF groups are prevailing in UHMWPE treated with XeF 2 and TbF 4 . Surface texture of UHMWPE treated with XeF 2 and with F 2 is quite different. Direct fluorination results in a higher polarity of the polymer surface when compared with treatment with XeF 2 . For the case of direct fluorination, both long‐lived peroxy and fluoroalkylradicals are formed. For the case of treatment with XeF 2 , only fluoroalkylradicals were detected. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 49:3559–3573, 2011

Practically all phosphorites contain impurities whose presence is undesirable in fertilizers. At the same time it is necessary to extract rare earth elements from phosphorites. Every year millions of tons of phosphogypsum are sent to waste dumps that have an adverse impact on the environment. None of directions for reprocessing of phosphogypsum has been implemented in the industry yet. The paper presents the results of studies aimed at implementing the steps to obtain environmentally friendly waste from the production of fertilizers

Bimetallic samples may be produced by casting St3 structural steel between sheets of Kh18N9T stainless steel in a mold, with subsequent hot rolling of the three-layer sheet. Such samples have a structure in which Kh18N9T stainless steel appears at the outer edge on both sides, while the core consists of St3 structural steel. Analysis of the boundary between the steels confirms the absence of defects: it is continuous and of high quality. The microstructure of the junction is investigated by optical, scanning-probe, and electron microscopy. Three structural components are observed from the pearlitic to the austenitic steel: a weakened section of the ferritic layer; a strengthened section of the ferritic layer; and a dark-etching layer at the austenitic steel. The following results are obtained by scanning-probe microscopy—in particular, the constantforce contact method—and optical metallography: on approaching the boundary from the St3 steel, a carbon- free layer with purely ferritic structure is observed, rather than the usual structure for low-carbon steel, which consists of a ferrite matrix with pearlite colonies. On approaching the boundary from the Kh18N9T steel, a carburized layer is observed. In addition, the boundary includes an intermediate carbide layer (depth up to 50 μm). The change in microhardness in the region where the St3 structural steel meets the external layer of Kh18N9T stainless steel indicates considerable increase in strength of the materials. Elemental microanalysis of the St3 steel–Kh18N9T steel boundary reveals the change in concentration of the alloying elements on approaching the boundary. The presence of chromium in St3 steel and the increase in carbon concentration in Kh18N9T stainless steel confirm that two opposing diffusional fluxes are formed: the diffusion of carbon from the St3 steel; and the diffusion of alloying elements from Kh18N9T steel. The resulting carbides explain the increased hardness of both steels close to the boundary.

The review describes the main methods of obtaining hydroxides and aluminium oxides (AO) of various structures from gibbsite. The promising techniques of obtaining AO adsorbents are discussed, namely the technique of thermal activation in the mode of pneumatic transport with gibbsite by heated air (TCA Gb) and the technique of thermal activation of gibbsite in centrifugal flash reactors (CTA Gb). The main methods of improving the adsorbent properties of AO, such as the optimisation of texture characteristics and phase composition, as well as the influence of the modification of aluminium oxide adsorbents, obtained using CTA and TCA technologies with cations of alkaline metals, are considered. It is shown that the modification allows a controlled variation of the characteristics of donor and acceptor active sites on the surface of adsorbents and, thus, a substantial increase in their adsorption activity, in particular, with respect to water vapour.

A study was made of the processes involved in the nucleation and propagation of Chernov–Luders bands in low carbon steels. It is found that the deformation bands are nucleated in the deforming sample at stress levels that are significantly lower relative to the upper yield limit. A sharp yield point is found to occur on the deformation curve, with its ascending and descending branches corresponding to the band nucleus “ingrowth”. Following the sharp yield point, a mobile Chernov–Luders band proper is observed for the yield plateau. The rate of deformation band fronts has been determined for both the band “ingrowth” and the band propagation stage. The occurrence of mobile band front(s) is considered. Thus, the conventional assumption that the deformation front is a boundary separating deformed and non-deformed material regions represents facts only approximately.

The change in ultrasound velocity in the plastic deformation of high-chromium 40X13 stainless steel with ferrite–carbide structure (initially), martensite structure (after quenching), and sorbite structure (after high tempering) is investigated. The loading curve is different for each state. In the initial state, the loading curve is practically parabolic. In the martensitic state, linear strain hardening is the only stage. In the sorbitic state, a three-stage curve is observed. The structure of the steel after different types of heat treatment is studied by optical and scanning probe microscopy. In parallel with the recording of the loading curve, the change in properties of the ultrasonic surface waves (the Rayleigh waves) in the steel under tension is measured. To determine the speed of the Rayleigh waves, rectangular pulses (length 100 ns) are generated periodically at the input of the emitting piezoconverter and the wave is recorded after passage through the sample by the receiving piezoconverter, which is connected to a digital oscillograph. The resulting digital signal is used to measure the time from pulse generation to the appearance of a signal at the receiver output. The distance between the converters is constant. The changes in the ultrasound velocity during active loading are determined by the plastic flow—that is, by the stages in the corresponding loading diagram. The structure of the steel determines not only the type of deformation curve in uniaxial extension but also the dependence of the ultrasound velocity on the strain.

To perform an effective function of an ultrasonic device for intensification of different technological processes a generator should have a system for an automatic frequency searching and tuning in terms of changes of the oscillation system resonance frequency. This article presents a system of phase-locked-loop frequency control (PLLFC) of ultrasonic generators with automatic resonance frequency searching in the given band of frequencies.

This work presents peculiarities of forming a structure, phase and chemical composition while welding medium-carbon steels (Steel 45) depending on a heat content of molten electrode metal droplets when using welding power sources having different power parameters. It was experimentally established that the power inverter provides the decreased heat input into droplets of electrode metal during the welding process. This stimulates obtaining a fine-grained structure of the deposited metal and heat affected zone, reduces the extent of the HAZ that enhances working properties of welded joints.

During the period from 1998 to 2007, a prospective cohort study of acute myocardial infarction morbidity cases as well as a "case-control" study of arterial hypertension was carried out. The risk of acute myocardial infarction was assessed as well as arterial hypertension; the dose-response relationship and the role of radiation in the mechanism of acute myocardial infarction as well as arterial hypertension development were studied. As a result of this study, a statistically significant increased risk of acute myocardial infarction among the male staff at the Siberian Group of Chemical Enterprises [standardized relative risk = 1.16 (1.04; 1.29)] exposed to external irradiation in comparison with employees unexposed to ionizing radiation was observed. A significant increase in the risk of acute myocardial infarction was observed at external radiation dose accumulation of more than 300 mSv [standardized relative risk = 1.46 (1.09; 1.91)]. The increase in arterial hypertension risk has been established among the analyzed group of employees exposed to long-term irradiation in the absence of the linear dependence of risk, based on cumulative dose of external γ-irradiation [risk due to external radiation dose in the range of 7.3-21.3 mSv = 1.6 (0.96; 2.51) and in the range of external radiation dose 21.4-68.5 mSv = 1.7 (1.04; 2.67) for 68.6-864 mSv = 1.6 (1.01; 2.57)]. This led to the conclusion that radiation can act also as a factor that might potentiate the negative effects of the "traditional" risk factors in the pathogenesis of acute myocardial infarction and hypertension.

The paper describes the construction principle of multi-point electro-optical system, intended to determine the spatial arrangement the source of the explosion in potentially dangerous protected object of complex shape, and formulated approaches to its simulation.

In this paper design features of laboratory sample of multipoint system to determine the arrangement of the explosion source were discussed. Description of a structural scheme of the laboratory sample of the system was showed.

This paper considers the problems of adjustment and calibration of electronic ultrasonic generators. The technique is offered and examples of adjustment of electronic ultrasonic generators are briefly described. Outcomes of tests are submitted. The possibility of monitoring key parameters (power consumption, current, supply voltage), with the help of the created calibration stand, is confirmed.

In this work is described the potential range of applications of ultrasonic technologies in conditions of small-scale enterprises and the problems which limit such applications caused by the absence of low-cost compact multipurpose ultrasonic technological devices. The problems arising during compact ultrasonic device development are considered, and possible solutions given. The engineering solutions applied during the design of an oscillation system and electronic generator, in order to increase efficiency, reduce dimensions and weight, simplify operation and expand the application range are described. In conclusion, the performance attributes and photos of compact multipurpose ultrasonic technological device pre-production models are presented.

The article describes the automated control system of the experimental setup for determining the parameters and characteristics of the explosion chamber for the study of parameters and characteristics of the the electro-optical system detect explosions.

The article describe the laboratory pattern of position pyrometric detector of explosion with field stop. The description of block diagram of the detector and design of optical system and electronics are provided. The processing algorithm for electronics of a laboratory pattern of the pyrometric detector is considered.

The paper considers the methods of preparing the difference schemes required for dynamic identification of the parameters of a DC motor as an object of the electric drives with control system during idling start-up. A system of differential equations describing the separately excited DC motor is reduced to the system of difference equations for constructing the discrete model. The authors have used three methods: direct difference, bilinear transformation method and multipoint approximation for writing the difference equations system. The estimations of the parameters of the discrete model based on the linear algebraic equations system applied this way were obtained by the inverse matrix method. Comparing the estimates obtained the authors detected the influence of the methods of constructing the object discrete model on the error in the parameters estimations obtained.

The article deals with sensorless method for determining the angular position of the rotor of a synchronous motor by means of superimposing a high-frequency signal. The scheme of the laboratory stand for the experiment to determine the angular position without the use of the position sensor was made. A technique for determining the angular position of the rotor with an accuracy of 30° was described. The logic diagram for its implementation was presented. The derivation of the formula for the calculation of the angular position of the synchronous motor rotor was presented. Findings during the experiment for determining the angular position sensorless were analyzed. Conclusions to reduce the cost and size of the drive system and increase its reliability were presented.

In this paper, we presented studies of the sliding friction without lubrication of Hadfield steel, ShKh15 bearing steel, and AISI steel 1020 against AISI steel 1045 upon applying an electric current with a contact density higher 100 A/cm2. We showed that the intensity of the surface layer deterioration increased with increasing current density. The catastrophic wear of materials begins at different values of the current density and at close values of the wear energy intensity. The dependences of the average contact temperatures on the current have been determined. The major conclusion is that it is impractical to harden the primary structure by alloys to achieve a low wear rate.